Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
10650Z7
The invention relates to data transmission systems for
the automatic wireless transmission of items of multi-digit
information between interrogation devices and response devices
which are mobile with respect to one another, such as carrier
units provided with energy supply, in particular to identify
railway locomotives at stationary interrogation devices, wherein
in a given frequency band within the microwave range each
interrogation device transmits an interrogation signal which
periodically changes its frequency, and from which any response
device moving past selects those respective frequencies assigned
to the item of information by means of filters which each consist
of a high frequency line resonator and which are tuned to
resonance for these fraquencies, sending back for each digit of
the information a given number of response frequencies to the
interrogation device, and wherein each response device is pro-
vided with a high frequency line section to which the filter
for the frequencies to be selected are in each case coupled, and
wherein furthermore for all the given frequencies there are
provided permanently tuned resonators which, to enable a desired
item of information to be set up, can be individually deactivated
by intense detuning or intense damping.
A response device of this type is known having an
arrangement of coaxial or waveguide resonators, each resonator
being provided with a mobile pin which can be plunged into the
resonator when necessary.
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One object of the present inyention is to provide an
improved response device of the type described above, inasmuch
as a determinate or total detuning or damping of the microwave
resonators is possible without mechanically moved components.
According to one aspect of the invention there is
provided an answering device in a system for automatic wireless
transmission of multi-digit information, particularly identify-
ing indicia on railroad cars between interrogation devices and
answering devices movable with respect to one another on movable
carrier units, wherein each interrogation device transmits an
interrogation signal which periodically varies its frequency
within a predetermined microwave frequency band to which the
answering device being moved past responds to frequencies for
each digit of the information and sends back to the interrogation
device a predetermined number of answering frequencies cor-
responding to each digit of the information, each answering
device comprising:
a. a plurality of resonators coupled to a high frequency
line section, said resonators each having a fixed frequency;
b. a microwave diode coupled to each resonator to switch
the resonator inoperative when a control voltage is applied to
said diode;
c. a control voltage means connected to the microwave
diodes for switching inoperative certain of said resonators to
set up the answering device for multi-digit information to be
transmitted; and
d. the resonators being constructed as container-like
hollow waveguides with head portions, the coupling of the micro-
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wave diode to the resonator taking place via an inductive
coupling element through the head portion of the resonator.
According to another aspect of the invention there
is provided an answering device in a system for automatic
wireless transmissions of multi-digit information between
interrogation devices and answering devices movable with respect
to one another on movable carrier units having an energy supply,
numbers of railroad vehicles being transmitted to stationary
interrogation devices, each interrogation device emitting an
interrogation signal altering its frequency periodically in a
prescribed frequency band situated in a microwave range from
which the answering device selects frequencies assigned to the
information as it moves past by means of resonators comprising
high frequency cup-shaped line resonators, said resonators being
tuned to the resonance of said frequencies for returning a
prescribed number of answering frequencies to the interrogation
device for each digit of the information, each answering device
having a high frequency line section to which the resonators for
the frequencies to be selected are respectively coupled, tuned
resonators being provided for all of said frequencies, said . -
resonators being individually switchable inoperative for setting -
up the multi-digit information by strong damping, a microwave
varactor or PIN-diode coupled in each resonator for detuning .- .
or damping the resonator by applying control voltages to the
microwave diode, said diode being provided as a diode-chip
integrated in an inductive coupling element insertable into an
aperture in a bottom of the cup-shaped resonator.
The fully electronic remote adjustment of the response
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device results not only in the attainment of a hiyh switching
speed, but also in a considerably greater reliability and a
longer life duration than in the case of remote adjustment by
means of mechanically moved components. In addition it is
possible to monitor the switching states of the diodes in a
simple fashion, which serves to increase the reliability.
Advantageously, a microwave PIN-diode is used, which
can be operated as controllable microwave resistance, or a
varactor diode which can be operated as controllable microwave
capacitance.
In response devices with coaxial or waveguide
resonators the microwave diode is advantageously coupled to the
resonator via an inductive coupling element on the base of a
container for the resonator, in which case the microwave diode
is advantageously in the form of a diode chip integrated in the
coupling element, which latter can be inserted into a bore in
the container base of the resonator.
Advantageously, the lines which serve to supply the
control voltage for the microwave diode are arranged on a plate
on the outside of a container at the base of the resonator.
Advantageously, the coupling can be effected
capacitively with a switching antenna.
The invention will now be described with reference to
the drawings, in which:-
Figure 1 is an explanatory equiYalent circuit diagramof a microvave resonator with a diode circuit connected thereto
to provide controlled damping;
Figures 2 and 4 show three exemplary alternative means
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of arranging the microwave diode in a coaxial resonator, when
the diode is to be connected to the central conductor; and
Figure 5 schematically illustrates an alternative
embodiment of a switchable microwave resonator.
The equivalent circuit diagram shown in Figure 1
consists of a d.c. voltage supply component I, a component II
comprising a microwave diode D, a coupling component III, and
a component IV comprising a microwave resonator in the form of
a parallel oscillatory circuit with an inductance L4 and
capacitance C4, shunted by a parallel resistor R4. The
individual components I to IV operate as follows:-
The component I includes a ~-element composed of shunt
capacitances Cl and C2 and a series inductance Ll, arranged in
the path from the d.c. voltage supply source to act as a HF
short-circuit, whereas the microwave diode D acts as a switch
or variable capacitor, the coupling component III serving to
couple the diode circuit to the resonator, and the resonator
determining the information to be produced from a responder
unit by virtue of its resonance frequency. The microwave
diode, whose impedance can be changed by a control voltage St
applied via the d.c. voltage supply line, is inductively
coupled to the resonator with a coupling factor k. Instead
of inductiYe coupling a capacitive arrangement may be used
for the coupling component III, and the microwave resonator of
component 4 may, for example be designed as a A/4 coaxial
resonator cavity.
Advantageously the microwave diode which is used is a
PIN-diode, which can be operated to provide a controllable
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microwave resistance. If no voltage is applied or if a blocking
voltage is connected to the PIN-diode, the latter exhibits a high
microwave resistance normally in the order of a few kOhm. If
a forward bias voltage is connected, the microwave resistance is
significantly reduced. With an appropriately high voltage e.g.
approximately 1 V, it is possible to make the microwave
resistance very small, e.g. approximately 1 Ohm.
With the correct selection of the coupling k of the
diode to the microwave resonator, when a negative control
voltage, or in an extreme situation even when zero volts is
connected, there is no significant damping of the resonator by
the relatively high diode resistance which is effectively in
parallel to the microwave resonator. On the other hand, if a
positive control voltage is connected, the resonator is subjected
to intense damping and thus rendered inoperative by the low
diode resistance now lying in parallel thereto.
Advantageously the microwave diode can be in the form
of a varactor diode, which can be operated as controllable
microwave capacitance. me connection of an appropriately
poled voltage generally a negative blocking voltage, results
in a change in the microwave capacitance presented by the
diode.
A continuously variable change in the capacitance can
take place if a diode of the type has a capacitance that
continuously increases with rising blocking voltage is used.
Thus by appropriately coupling such a diode to the microwave
resonator it is possible for a control voltage to continuously
tune the resonance frequency of the resonator within a specified
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range.
However, a change in the capacitance can also be
produced suddenly, and this fact can be employed to carry out
determinate changes in frequency with control voltages which can
fluctuate in a specific range. For example in the case of the
so-called "dual-stage" diode, by means of an appropriate
doping of the semiconductor material it is provided that the
diode can fundamentally assume only two determinate capacitance
values; i.e. when a control voltage is connected the diode will
assume a first capacitance value CA below a specific applied
voltage and a second capacitance value CB when the applied
voltage is above that specific voltage.
Figures 2 to 4 show variants of the microwave diode
coupling to a resonator in the form of a coaxial resonator
cavity. In Figure 2 the diode D is arranged inside the
resonator, in Figure 3 it is arranged inside a bore 3 in the
base of the resonator, and in Figure 4 it is arranged outside
the resonator. Here the coupling is in each case effected
inductively to the container base, the coupling component being
connected through the bore 3 and terminating at a point on
inner conductor 2 of the coaxial resonator cavity 1. However,
the coupling component can be input coupled into the resonator
either inductively or capacitively, so that the insertion can ~:
take place at the base of the coaxial resonator, at the side
or at the open end. The microwave diode D is in each case
driven by a d.c. voltage supply component consisting of the ~ -
elements Ll, Cl and C2, the shunt capacitances Cl and C2 each
having one electrode connected to the outer surface of the
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coaxial resonator 1. The connection of one termination of the
coupling element to an inner part of the resonator, which
proves difficult in the case of inductive coupling, can be
avoided by returning this end to terminal at the upper surface
of the resonator.
Figure S shows an embodiment of a switchable resonator
with an insertable coupling component 4, an integrated diode
chip D and a drive plate 5. The installation of diodes in
glass envelopes or the direct installation of glass-passivated
diode chips ensures a particularly simple and cost-favourable
construction of the resonator. Due to its small dimensions,
a diode chip can be favourably integrated into the coupling
component, as also in fact provided in the exemplary embodiment.
The coupling component 4, together with the diode chip D,
is inserted into the bore 3 in the base of the coaxial
resonator 1, the diode chip D being located more or less in
the region of the bore, and the coupling component 4 projecting
perpendicularly into the resonator cavity. The d.c. voltage
supply component is arranged on a drive plate 5 which is
arranged on the outside at the base of the coaxial resonator 1.
The electric connection of the d.c. voltage supply line to
the diode chip D and the coupling component 4 takes place
via a solder terminal 6.
With the aid of the various diode types it is possible
to produce a series of device variants. In the response
de~ice it is possible to code _ digits with the resonators.
In a system operating in a 2 from 5 code, for each digit two
or three resonators are required in order to represent the
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10650Z7
digits O to 9 in an inverse ZSC 3- or a ZSC 3 code. The
following illustration shows the frequency positions and
occupancies in the example of the number 8 for both codes:- -
normal ZSC 3 = X X
inverse ZSC 3 = X X X
Frequency 1 2 3 4 5
If the resonators are damped by PIN-diodes, and two
resonators are used per digit, the information is changed by
switching off or switching over information blocks. When
five resonators per digit are used, any necessary digits
from O to 9 can be set up for each position. Of the five
resonators, in dependence upon the desired digit, two or three
resonators are selectively rendered inoperative with the aid
of the PIN-diodes so that if necessary the entire item of
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1065~327
information can be changed.
In the case of continuous tuning by varactor diodes,
if two resonators per digit are used, each resonator is detuned
in determinate fashion within the useful frequency range. In
this case each resonator must be able to be selectively tuned
in determinate fashion to any one of four frequency positions;
for example the resonator 1 can be tuned from the frequency
position 1 to 4, and the resonator 2 can be tuned from the
frequency position 2 to 5. If necessary the entire item of
information can be changed. The resonators which are to be
disconnected can also be detuned, with the aid of the varactor
diode, in a range outside the useful band, resulting in a total
detuning. In the event of total detuning, the response device
can again be constructed with two resonators per digit, or with
five resonators per digit, the mode of operation corresponding
to that already described for damping by means of PIN-diodes.
In the case of a sudden tuning by means of semicon-
ductor diodes, which are capable of assuming a plurality of
discrete capacitance states, each resonator can for example
assume two resonance frequencies. Thus in the case of two
resonators per digit, the digit can be set to four different
numbers, and in the case of a plurality of resonators per digit
there is a corresponding increase in the number per digit that
can be set.
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